Magnetic recording hard disk drives that utilize a transducer mounted on a slider for reading and/or writing data on at least one rotatable magnetic disk are well-known in the art. In such systems, the slider is typically attached to an actuator arm by a suspension system and the slider is positioned very close to the disk surface. The combination of the slider and suspension system is referred to as a head suspension assembly.
The separation between the slider and the disk surface is referred to as the flying height. In a conventional disk drive, the slider rides on a cushion of air generated by the rotation of the disk and the flying height is influenced by factors such as the rotation of the disk, the aerodynamic shape and attitude of the slider and the load applied to the slider by the suspension.
As the storage density of magnetic disks increases, it is necessary to decrease the flying height below the heights conventionally used. For example, in disks with storage densities of 1 to 2 GB/in.sup.2, the required flying height is in the range of 35 to 50 nm.
In manufacturing head suspension assemblies, the current industry practice is to adjust the load of the suspension to a predetermined value before the slider is attached. The suspensions are preformed so that they have a higher load than is desired for operation in the disk drive. The suspensions are then positioned on a load measuring cell and heated with focused light from an infrared lamp for a few seconds. The duration of the heating is controlled so that the load after relaxation reaches the desired value. In the process the entire suspension gets heated to several hundred degrees Celsius. Because of this heating, the slider cannot be mounted on the suspension before the load adjustment process, and the process cannot be used with an assembled disk file. Additionally, the process only provides a method for decreasing the load.
Two other parameters associated with the slider are the roll and pitch static attitudes. The roll and pitch static attitudes are dependent on the components of the suspension and on the flatness of the slider, as well as on the suspension assembly processes. These factors also affect the flying height of the slider. Some manufacturers mechanically adjust the roll and pitch static attitude after assembly by bending a suspension component such as the flexure.
Other methods are known for adjusting the flying height of the slider. For example, Pohl et al., in U.S. Pat. No. 4,853,810, disclose the use of a tunnel current electrode for adjusting the flying height. Owe et al., in U.S. Pat. No. 5,012,369, disclose the use of a suspension having a screw for adjusting the flying height. IBM Technical Disclosure Bulletin, vol. 34, no. 10B, p. 242-244 (March 1992), discloses an automated fly height tester that utilizes a robot to position the head suspension assembly on a quartz disk where the load is adjusted mechanically or with an infrared gram load adjustment system.